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Sometimes, the deadliest hazard is also the most unassuming. Confined spaces, which come in various shapes and sizes, certainly fit the bill.

A confined space is dangerous because it is not designed for entry by human beings and once inside, it is often difficult to get out. They present a danger not only to those who work in them, but also to would-be rescuers, who account for an estimated 60 per cent of fatalities associated with confined spaces, accoridng to the Canadian Centre for Occupational Health and Safety in Hamilton, Ontario.

Apart from the risks of getting trapped or falling inside a confined space, the presence of hazardous gases is an all too-familiar risk. To better understand how to safely work in and around these pockets of space, employers must first determine just what exactly is a confined space, which can be challenging as many are ambiguous in nature.

Confined Defined
Despite its name, a confined space is not necessarily a small area. The Canadian Standards Association (CSA) defines it as “a workspace that is fully or partially enclosed, is not designed or intended for continuous human occupancy and has limited or restricted access, exiting or internal configuration that can complicate provisions of first aid, evacuation, rescue or other emergency response services.” Confined spaces can be found across industries, such as winemaking, welding, construction, sewer works and farming. Think vaults, silos, culverts, tanks, ship holds, storage units, cellars, wells, manholes and tunnels.

“It can be just about any kind of area that is contained,” says Dave Angelico, president of Air Systems International Inc. in Chesapeake, Virginia. He cites as examples airline employees going into the wings of a plane to clean fuel cells and brewery workers entering beer vats with low oxygen content.

Unless proven otherwise by a hazard identification and risk assessment, a confined space should be considered hazardous by employers, notes the CSA Z1006 Management of Work in Confined Spaces standard. “It is almost impossible to define a confined space because there are just so many variants,” says Sean Donovan, business development manager at MSA in Toronto.

The hazards associated with confined spaces vary considerably. Ross Humphry, general manager with Canadian Safety Equipment in Mississauga, Ontario, says the biggest concern in most industries is oxygen deficiency and combustible and toxic gases. They include hydrogen sulphide, which can paralyze the sense of smell at high concentrations, and carbon monoxide, carcinogenic and explosive gasoline and methane. These gases are often volatile and have unique properties that contribute to their unpredictability, making it challenging for occupational health and safety officials to regulate and standardize safe practices.

Manish Gupta, national account manager at Draeger Safety Canada Ltd. in Mississauga, Ontario, says gases tend to sit in layers. Depending on its weight, heavy gases might sit near the floor; others might linger around the breathing zone, while those that are lighter than air will hover at the top. Simply entering a space can stir up the air and conditions can change from safe to unsafe very quickly, Gupta notes.

Know and Act
Angelico stresses that the atmosphere of a confined space must always be tested prior to entry, followed by ventilating and purging for the proper amount of time based on the air changes required. He also recommends using at least a three-gas monitor capable of detecting combustibles, oxygen and hydrogen sulphide gases.

If other known hazards exist within a confined space, a meter that can monitor the hazard should be used. “The meter should be able to pull a sample from the deepest part of the confined space prior to entry to check for harmful gases or deficient oxygen levels,” Angelico adds.

Gupta says multi-gas monitors are useful as they can detect numerous hazards simultaneously. For added safety, he recommends that a personal gas monitor be worn near a worker’s breathing zone. “It is not something you take down with you and strap on to the wall,” Gupta cautions. Neither should it be worn on the hip like a cellphone. “It should be worn up close, like on your lapel or on your top pocket, closer to your breathing zone so if there is a problem, you will know it right away.”

For gas monitors to function at peak performance levels, diligent testing and calibration are required since the conditions in a confined space can change rapidly. “From a safety standpoint, I would say it should be calibrated before each use,” Angelico advises, noting that most manufacturers recommend a bump test or a quick calibration prior to use to make sure that the unit is functioning properly.

Gas detectors today are also designed to be more user friendly, Gupta observes, noting that workers in the past had to be trained on how to perform bump tests and calibrations. “Now, we have bump test stations where you just put in your gas monitor and it automatically performs the test and lets you know if they pass or fail. They will even do an automatic calibration if the gas monitor fails the bump test.”

In operations where atmospheres are changeable or contain different hazardous gases, Draeger offers gas monitors with plug-and-play technology, which allows sensors that are not required to be unplugged to suit specific workplace needs. Settings on the gas monitor can also be changed by using the manufacturer’s software.

A confined space is one area where assuming the worst will serve one in good stead. Using the right instrument capable of detecting the types and concentration of gases in an enclosed area is a first step. Once the gas levels have been determined, Angelico says ventilation of at least 10 to 15 minutes or longer should be conducted, depending on the size of the space. He estimates that eight to 15 air changes should be achieved prior to entering the space.

Ventilation blowers should be set back a minimum of six feet from the opening of the confined space to prevent exhaust gas from being sucked back in by the blower and blown down into the confined space.

Once the initial ventilation is completed, the ventilation system should be turned off and the atmosphere re-tested to verify that the space is safe for entry. If a safe meter reading is achieved, continuous ventilation should be maintained for the duration the space is occupied, he adds.

In Peril
Understanding how a worker’s tools can create a safety problem is also vital. For example, an employee working in a confined space where a combustible gas might be present must be equipped with non-sparking tools.

As the situation in a confined space can change at the drop of a hat, Donovan says a gas detector’s reaction time can often determine if a worker makes it out in time before serious injury occurs. “You want something that reacts the quickest, because that is what is going to save lives,” he suggests.

Rather than take the canary-in-the-mine approach, the safest way to determine if a confined space contains hazardous gases is to use a probe.

Apart from the dangers of combustible and toxic gases, Chuck Roberts, 3M Canada’s marketing supervisor of fall protection in London, Ontario, says workers are also vulnerable to falls from heights. This risk necessitates the provision of fall protection equipment, such as harnesses, anchors, lanyards and lifeline systems.

While fall protection equipment is useful when hoisting rescuers down a confined space to retrieve a worker who is injured or has succumbed to hazardous gases, Humphry laments that the knee-jerk reaction of peers diving in to rescue their fallen colleague is an all-too common scenario, often with fatal consequences.

Instead of attempting a rescue that could endanger one’s life, Humphry advises employees to consult first responders and determine whether or not a rescue mission can be attempted by staff or requires further assistance.

If it is determined that the rescue can be safely performed by the employer’s own retrieval crew, those workers must be properly equipped with respirators. Humphry says his team recommends the use of a remote supplied-air respirator instead of a self-contained breathing apparatus, which is bulky and may not fit into the entry way of a tight, enclosed space.

Price is Right
Technological advances in equipment to meet the industry’s oh&s needs have made tools, such as respirators and gas detectors lighter, smaller and more reliable. However, some employers who have confined spaces on their premises may be hesitant to invest the time and resources needed to perform adequate testing or purchase the right equipment.

“One of the biggest things with confined spaces is that sometimes, you will have an operation that you need to go into once a year, so they don’t want to invest in fall protection and gas monitors for something that they do [annually],” Gupta suggests.

After factoring in personal and auxiliary gas detectors and monitors, fall protection equipment, respiratory tools and personal protective gear, confined space equipment can set an employer back by thousands of dollars.

“From a cost perspective, that might seem like a lot,” Roberts says. But should an emergency or a worker fatality occur as a result of inadequate protection, “the lawsuits that happen are a lot more than the initial investment,” Roberts suggests.

One solution is renting equipment for confined space entry, which Gupta says many companies are starting to do. A third-party company can also be contracted to conduct the necessary training programs, he adds.

That said, a higher price tag does not necessarily mean a better product. Ultimately, functionality is the deciding factor when choosing a safety product that best suits workplace needs

Sabrina Nanji was the former editorial assistant of Canadian Occupational Health and Safety News.